+ Biologic Behavior

  • CSA is a malignant cartilage-producing neoplasm arising de novo within bone
  • CSA is the 2nd most common primary bone tumor (5%-10%), but uncommon in the appendicular skeleton
  • CSA should be differentiated from chondroblastic OSA
  • Etiology is unknown but can arise at multiple cartilaginous exostoses sites or previous bone lesion
  • Median age 8.7 years
  • Breed predisposition: Golden Retriever
  • 61%-91% CSA occur in the axial skeleton (i.e., nasal cavity [26%-36%], ribs, pelvis, vertebrae, and skull)
  • Other CSA sites include the appendicular skeleton (<20% data-preserve-html-node="true" to 26%), digits, os penis, and extraskeletal sites (i.e., mammary gland, heart valves, aorta, larynx, trachea, lung, and omentum)
  • CSA is slow to metastasize

+ Staging

  • CSA is classified as primary or secondary:
  • Primary CSA: de novo tumor unassociated with preexisting lesion)
  • Secondary CSA: tumor associated with preexisting cartilage lesion (i.e., osteochondroma or multiple cartilaginous exostoses)
  • Central (i.e., medullary) and peripheral (i.e., periosteum) classification is only applicable to secondary CSA

+ treatment

  • Surgical resection is the preferred treatment for cats and dogs with CSA
  • Radiation therapy is recommended for unresectable lesions
  • Chemotherapy is recommended for grade III CSA
  • Ciprofloxacin, a fluoroquinolone with known toxicity to chondrocytes, inhibits chondrocytic proliferation and induces apoptosis in vitro and may be toxic to CSA cells

+ Prognosis

  • Tumor location is prognostic with CSA in the skull, nasal turbinates, and appendicular skeleton having a better prognosis than rib CSA
  • MST 210-580 days for dogs with nasal CSA and metastasis is very rare
  • MST 1,080 days for dogs with rib CSA
  • MST 201-540 days for dogs with appendicular CSA treated with limb amputation ± chemotherapy
  • 12-month survival time 17% and 24-month survival time 13%
  • Histologic grade: I, II, and III
  • Histologic grade is an important prognostic indicator for CSA of the same site